If you’ve ever been very sick, you may have used this expression. Because dogs eat just about anything they find, they often get sick. So it’s fitting to describe someone who is not feeling well as being “sick as a dog.” Arf!

And while this is a good enough explanation for a kid, something about the “sick” portion didn’t sit well (pun!) with me at all. If being “sick as a dog” means I get to puke & recover as quickly as possible that’s hardly a bad thing, right?

There are several expressions of the form sick as a …, that date from the eighteenth and nineteenth centuries. Sick as a dog is actually the oldest of them, recorded from 1705; it is probably no more than an attempt to give force to a strongly worded statement of physical unhappiness. It was attached to a dog, I would guess, because dogs often seem to have been linked to things considered unpleasant or undesirable; down the years they have had an incredibly bad press, linguistically speaking (think of dog tired, dog in the manger, dogâ€™s breakfast, go to the dogs, dog Latin â€” big dictionaries have long entries about all the ways that dog has been used in a negative sense).

“Sick as a dog,” which means “extremely sick” and dates back to at least the 17th century, is also not so much negative as it is simply descriptive. Anyone who knows dogs knows that while they can and often will eat absolutely anything, on those occasions when their diet disagrees with them the results can be quite dramatic. And while Americans may consider themselves “sick” when they have a bad cold, in Britain that would be called “feeling ill.” “Being sick” in Britain usually means “to vomit.”

So “sick” – in this sense – is not what I am feeling today. Today I’m merely ill. Irritable, cranky, creaky, headachy and tired, but not sick. Thankfully, not “sick as a dog” either.

Also, here’s an Aerosmith song of the same title for your afternoon enjoyment: